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A control scheme using space vector modulation for the modular multilevel matrix converter (MMMxC) without circulating current control is investigated. The circulating current flows spontaneously among all the nine arms to balance capacitor voltage of cells. A small arm inductor is inserted into each arm to suppress the di/dt and peak value of transient arm current at the moment of switching the cells...
Single-phase two-stage inverters generally use an intermediate capacitor to buffer the power imbalance between DC input and AC output. However, the resultant low-frequency voltage ripple on this intermediate capacitor may produce low-frequency ripple at the source side, especially when the front-end dc/dc converter operates in continuous conduction mode (CCM). Some common solutions to reducing this...
Variable carrier single rate deadbeat control method for low carrier frequency was proposed. In the large capacity inverter system, the carrier frequency range is limited to relatively lower frequency range, the trade off between the control accuracy and the efficiency should be considered. Digital hysteresis control was applied to the inductor current, suitable carrier frequency was adopted in every...
A new ripple current reduction method utilizing a LLC type ripple current steering circuit is proposed in this paper to significantly reduce 100Hz ripple current in an isolated DC-AC dual active bridge (DAB) converter. Unlike some of the proposed ripple reduction methods for which auxiliary circuit consists of additional switches is applied, this new method benefits from less switching components...
This paper investigates a two-stage low-frequency square-wave (LFSW) electronic ballast with a combined analogue and digital control. The first stage of the ballast is a power factor correction (PFC) converter and the second is a half-bridge (HB) converter with an igniter. The advantage of the proposed scheme compared to conventional LFSW ballasts, is including an improved modified HB circuit. This...
A control method of reducing transient-glitch voltage in variable frequency (VF) DC-DC converters is proposed in this paper. By modulating the period between two hopping frequencies to a calculated time length, the proposed control method keeps the average of the inductor current undisturbed and leads to less transient effects. Simulation results show the improvements on the transient-glitch voltage,...
This paper proposes the high voltage gain quadratic boost converter for supplying standalone ac loads using renewable power supply that generates dc power at low voltages. A fixed frequency SMC has been proposed in this paper to regulate the dc link capacitor voltage. The conventional SMC has variable switching frequency while leads to the damage of passive components as well as unpredictable response...
This paper studies and compares control schemes for fully-integrated step-up dc-dc converters. The paper analyzes both a pulse-width-modulated and a pulse-frequency-modulated control schemes, and discusses the differences in terms of load currents and output voltages. Both control schemes were designed and simulated in a CMOS 65-nm technology. The paper also compares the analytic models to simulation...
This paper is focused on the possibilities of implementing an auto-adaptive control, without a phase-locked loop circuit, for the operating frequency in an induction heating system with single-phase voltage source inverter and resonant L-LC load. Based on the phasor diagram of the equivalent resonant load under resonance condition, three possibilities have been identified to express an error to be...
This paper proposes input-parallel output-parallel (IPOP) three-level (TL) DC/DC converters with the interleaving control strategy, which is composed with two four-switch half-bridge TL (HBTL) DC/DC converters featuring with simple and compact circuit structures. Due to the IPOP structure, the component current stresses in the proposed converters are reduced. More significantly, the combination of...
The paper presents the energetic performances of a system used for drying of current transformer from 110 kV Ciungetu power station. In fact, the drying process is based on an induction heating system that contains a half-controlled rectifier and a voltage source inverter that operates with resonant load. Two frequencies are taken into consideration for the inverter control. The former is the resonance...
A new dual-output LLC resonant converter is presented for high power density and high efficiency dual-output application. A new control freedom is provided by replacing two diodes in the secondary-side rectifier with two MOSFETs. Variable frequency modulation plus secondary side phase-shift modulation scheme is adopted to realize precise regulation of both the two outputs simultaneously. Meanwhile,...
In electromagnetic resonance based wireless inductive power transfer (WIPT) system, voltage gain is determined by the coil inductances and the coupling coefficient of the power transmitting coils and frequency of operation. In this paper, voltage gain of an electromagnetic resonance based series-parallel compensated WIPT system is analyzed. Different control schemes are discussed to achieve high efficiency...
This paper focuses on the application of modular multilevel matrix converter (M3C) in fractional frequency offshore wind power system (FFOWPS). M3C is one of the direct ac-to-ac power converters capable of bidirectional power flow. It has many advantages compared with traditional cycloconverter, so it is more competitive and promising to be used in FFOWPS. This paper constructs an equivalent circuit...
One important type of power conditioning systems in photovoltaic (PV) application is the string inverter which requires small input voltage and current ripple. In addition, high-efficiency and high-power density are also the critical requirements for string inverter system. So the input voltage and current ripple cannot be easily rejected by paralleling large conventional electrolytic capacitors in...
Load Frequency Control (LFC) is employed in a system to maintain the scheduled system frequency and tie line power of an interconnected area within the prescribed limits. In this paper load frequency and tie line power of three area interconnected power system is controlled first by conventional PID controller only and then a combination of Superconducting magnetic energy storage (SMES) and the PID...
This paper presents a high power density 2 kW single-phase inverter, with greater than 50 W/in3 power density and 90% line-cycle average efficiency. This performance is achieved through innovations in twice-line-frequency (120 Hz) energy buffering and high frequency dc-ac power conversion. The energy buffering function is performed using an advanced implementation of the recently proposed stacked...
DC-DC power supplies are used in almost every sphere of engineering like PC/laptop, chargers, spacecraft, HVDC transmission etc. A steady source of voltage is required irrespective of any changes in line, load condition & parametric uncertainties for their application. The steady state behaviour of converter can be explained by the topology of converter and the controller has taken an important...
Total Harmonic Distortion (THD) of a voltage or current signal causes power system losses, apparatus overheating and increases the power bills. This paper proposes the design and implementation of a transformer less single-phase inverter system that produces an output voltage of desired magnitude and frequency at a very lower THD. In ‘general inverter system’, a lower DC voltage is inverted into lower...
This paper presents a random frequency hopping with triangular ramp control for harmonic reductions in a dc-dc converter. The relationship between “the sawtooth and triangular ramp signals” and the inductor current is analyzed, and the two ramp signals are implemented into the converter to compare the variation of output voltage. When the switching frequency hops, using triangular ramp keeps the small...
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